Ahna Johnson pedaled furiously, biking to welcome a new “citizen of the whirled” with freshly pureed bananas and strawberries.

The 27-year-old’s churning legs didn’t propel her down Chapel Street. They powered a bike-mounted blender loaded with yogurt and frozen fruit. Hopping off the saddle, Johnson poured the potion in a cup and handed it to a customer.

That scene unfolded Friday on Chapel Street, where Johnson was plying her trade as New Haven’s only pedal-powered purveyor of natural fruit smoothies.

Johnson, who operates under the name Fruit Whirled, is kicking off her first full summer as an eco-friendly food-cart operator. She’s bringing to fruition an idea born from travels in South America, frustration with the stress of a more conventional job, and a commitment to keeping people and the planet healthy.

Johnson’s day began with a biking commute from her parents’ house, down Orange Street into town, guiding her single-speed bicycle food cart around potholes. Johnson found the cart on Craigslist in New Jersey last year, after hitting upon her business inspiration a couple years earlier.

She had been traveling with her cousins in Ecuador at the time, on a two-month trip through Central and South America. As they traveled, they sampled delicious smoothies, widely available because of an abundance of fresh fruit. “That should be the case at home,” they said, and began to speculate about how one would make a smoothie business.

You’d want it to be eco-friendly, they agreed, and wondered how to power a blender without carbon-generating electricity. “Wait, no, you could pedal it!”

Johnson pedaled her cart Friday to Chapel Street, and set up in front of the Yale art gallery. She opened her umbrella and set out a chalkboard advertising the day’s smoothie flavors: banana-strawberry and tropical mango. Johnson blended up a couple of sample batches to test out a new method, using frozen fruit instead of fresh fruit and ice.

“Too thick, much too thick,” she said, adding water to the pitcher.

“Come on, I know you want a smoothie,” she said, offering samples to passersby.

Dan Vieira, stopping by the gallery, was her first customer, attracted by “the uniqueness of it,” he said. After Johnson served him his drink with a stick of celery as an “edible spoon,” Vieira declared the smoothie delicious. “Strawberries and bananas—you can’t go wrong.”

After she returned from South American to the U.S., speculation about pedal-powered smoothies percolated in Johnson’s brain. She continued to consider it even after she got a job as a project manager with a Connecticut solar-power company. She was living up to her environmental ideals, “but it was making me mean and sad.” She was tired and short-tempered from long days and little rest.

She quit the solar job and—after a trip to Israel to win gold on the American women’s soccer team in the 2013 World Maccabiah Games (“It’s like the Jewish Olympics”)—Johnson started Fruit Whirled.

After accepting Vieira’s credit card payment using an app on her iPhone, Johnson tweeted her location, trying to think of a clever line to attract customers. “People of the whirled!” she ventured.

“Right now, I’m getting my name out there,” Johnson said. As a new vendor on the street, it’s going to be hard to make much money, she said, “It’s going to be all about the festivals.”

Johnson said she’s found the most success at fairs and public events, like the Hamden Food Truck Festival. She’ll be at the upcoming Arts & Ideas Festival and at the Wooster Square Farmers Market starting in July.

She also does private parties. She has pushed her single-speed cart up Prospect Hill for a bat mitzvah, and pedaled it 10 miles to Lighthouse Point for a benefit for Solar Youth.

“That’s bad ass,” said a passerby on Chapel Street, noticing Johnson’s “fender blender.” “I’ve never seen that before.”

Johnson offered to sell him a smoothie. He looked at the three sizes of compostable cups, with prices written on them. “Wow. $3.50. I can’t do that.”

Making fresh smoothies isn’t cheap, Johnson said as the man walked away. She would like to charge even more, but tries to keep the smoothies under $5. The small size is $3.50, medium is $4.50, and the large is $5.50.

“If I was selling Coke and ice cream, I would make a killing,” she said. She could buy sugary treats cheaply and sell them easily. “But I would feel bad about it.”

Johnson said she wants to sell a healthful product, and keep her carbon footprint as small as possible. Meanwhile, her parents, while very supportive of Fruit Whirled, are worried about her making enough money, Johnson said. They’d like her to do something with her Fairfield University degree in physics and information systems.

Kristianne Hall (at right in photo), who works across the street at Hello Boutique, sprang for a smoothie. She said she usually sees a barbecue truck parked on the block, and was surprised to see Johnson’s rig instead.

“I was like, what kind of cart is that?” Hall said.

“It’s amazing,” she said, after sipping her smoothie.

“Give me a $4.50,” said Floyd LeSane (pictured), who works security at the gallery. “Fresh and natural. Ahh, I feel energy already!” he announced as Johnson began pedaling.

“I love a smoothie,” LeSane said. “Good day for it, and she ain’t killing the ozone! Everybody wins.”